1. Field of the Invention
The present invention relates to a consumable supply management system, a consumable supply management method, and a consumable supply management program for managing consumable supply used for image forming apparatuses such as printers, copiers, or the like.
2. Description of the Background Art
Image forming apparatuses (e.g., printers, copiers, facsimile machines) typically need consumable supplies (e.g., sheets, toner) used for image forming operations. Accordingly, if such consumable supplies are completely consumed (referred to as “consumable supply end”), the image forming apparatuses cannot continue image forming operations, which is inconvenient for a user.
In view of such consumable supply end condition, a client (or user) may need to stock some spare consumable supplies, and place an order when it is determined that consumable supply end is to occur in the near future. Typically, consumable supplies are delivered to a client upon such order being placed, but such delivery process needs a given time including transportation time such as several days. Among various consumable supplies, toner may need more time to be delivered than other supplies such as sheets of recording media such as paper or the like.
Accordingly, one method has been devised to detect a toner-near-end condition before a toner end condition occurs, and then place an order for toner delivery when the toner-near-end condition is detected. Further, another method has been devised to detect and report a toner-near-end condition to a toner supply management server so that the toner supply management server is used to manage toner inventory at a client.
However, if the toner end condition occurs so quickly after detecting the toner-near-end condition that toner cannot be delivered to the client in time to continue image forming operations without interruption. In such a case, the client cannot use the image forming apparatus until a new toner bottle is delivered.
In view of such situation, several methods have been devised to detect toner consumption amount more accurately. For example, JP-2003-39789-A discloses a method of reading charge quantities of an electrostatic latent image formed on a photoconductor drum using an electronic sensor, and predicting toner consumption amount based on the charge quantities. Further, JP-2003-39789-A discusses a method of detecting a change in a toner remaining amount by detecting a change of electrostatic capacitance of the toner, and a method of detecting a toner remaining amount by counting the number of dots used for a latent image forming operation. Then, based on the detected remaining toner amount, a toner delivery order is placed.
By contrast, JP-2004-37743-A discloses a system to detect toner consumption amount by measuring toner flow amount. In JP-2004-37743-A, toner is supplied from a toner container (e.g., large capacity container) to an image forming engine using a toner supply unit having a flow meter, which detects toner flow amount. Accordingly, by detecting the toner flow amount using the flow meter, toner consumption amount for a given period of time can be detected.
However, the toner-near-end condition may be falsely detected even if toner still exists in a toner container in an amount sufficient for image forming operations.
For example, in JP-2003-39789-A, the number of pixels composing an electrostatic latent image on a surface of photoconductor drum is counted. Accordingly, if the photoconductor drum degrades over time, a tone adhering amount on the photoconductor drum may change, by which toner consumption amount may not be computed correctly. Further, the tone adhering amount during development may fluctuate due to environmental conditions such as temperature and/or humidity, making correct computation of toner consumption amount hard to attain.
Further, in JP-2004-37743-A, the flow meter measures toner flow amount. However, because toner amount flowing in a toner supply route may be too small, toner consumption amount detected by the flow meter may not match correctly an actual toner consumption amount from the toner container. Consequently, the toner consumption amount predicted by such method may deviate significantly from the actual toner consumption amount from the toner container.
Under the above-described system, a toner-near-end condition may not be correctly detected, and thereby a new toner bottle may be delivered unnecessarily to the client based on an incorrect detection of toner-near-end condition. For example, at a given time, a toner-near-end condition may be detected by a toner management system, which manages toner container delivery, and then the toner management system delivers a new toner container to the client. However, such toner-near-end condition may be canceled soon after. For example, at the toner-near-end condition, the client may remove and shake the toner container, and re-install the same toner container in the image forming apparatus. In such a case, the toner-near-end condition can be canceled and an image forming operation can be further continued. Then, another toner-near-end condition is detected by the toner management system again, and then such another toner-near-end condition is canceled again soon after. When such another toner-near-end condition is detected, the toner management system delivers another new toner container again to the client. Accordingly, if a toner delivery order is automatically placed whenever the toner-near-end condition is detected by the toner management system, consumable supplies such as toner container may be delivered to and stocked at a client's location, exceeding a necessary stock level. Such over-stocked condition is not convenient for the client because over-stocked consumable supplies require a larger stock space. Further, such over-stocked condition is not convenient for the client because if the client changes the image forming apparatus from one model to another model, such over-stocked consumable supplies for one model may not be usable in the new model.